Electron oscillator



July 20, 1948. E. s. v. PATTAMALY 2,445,690

v ELECTRON OSCILLATOR Filed May 22, 1945 V Inventor 24 mmun s.v. PHTTAMALY By Attbrney Patented July 20, 1948 ELECTRON OSCILLATOR Elavathur Subramanian Viswanathan Pattamaly,

Kannimangalam, Nemmara Post, India Application May 22, 1945, SerialNo. 595,211 In Great Britain June 2, 1944 3 Claims. (01. 250-36) This invention relates to electrical oscillators or generators of high frequency oscillations embodying electron discharge tube circuits and to electron discharge devices for use in such circuits.

The invention aims at providing a simple form of circuit by which the generation of very high frequencies is possible.

One object of the invention consists of an electron dischargetube furnished with a plurality of grids and only a single anode with the same interelectrode constants between each of said grids and the other electrodes of the tube.

Another object of the invention consists of a circuit connection for an electron discharge tube furnished with a .plurality of grids but only a single'anode with means for applying to the different grids of the tube which serve as control electrodes in order, voltages with equal phase displacements lagging or leading, and means for applying a bias voltage to the grids whereby the anode current due to the action of one grid is cut off as the anode current due to the next grid begins to flow.

A further object of the invention is a circuit for generating electrical high frequency oscillations comprising an electron discharge tube with a plurality of grids or control electrodes, but only a single anode having the same inter-electrode constants between each of said grids and the other electrodes with circuit connections for applying to said grids in order, voltages with a phase displacement lagging or leading of an angle of 369 electrical degrees divided by the number of grids and operated so that the frequency of the anode current is the product of the frequency applied to any one grid and the number of grids.

Instead of embodying a plurality of grids in a single envelope, each grid or some of them only may be included in separate envelopes with the anodes in the different envelopes connected directly together, and the cathodes connected directly together with each of the resulting tubes having the same characteristics so that the equivalent of a single discharge tube with its envelope containing a plurality of grids is obtained.

In such arrangements, as mentioned above, if the fundamental frequency to which each of the grid circuits is tuned is utilised, the frequency can be, as already indicated, the product of the frequency of the tuned oscillator circuit and the number of grids employed. A filter may be interposed in the output circuit arranged only to pass a single harmonic. Then the frequency available is the product of the fundamental frequency of the tuned circuit, the number of grids,

and a factor corresponding to the harmonic utilised. In the case of the fifth harmonic, this last factor is 4. The frequency thus obtained can again be increased by adding one or more additional stages embodying a further tube with a plurality of grids so that in this way, a very high ultimate frequency may be obtained.

The invention will now be further elucidated by reference to the accompanying drawing which is a diagrammatic showing of one embodiment of the invention in which an oscillator is formed of an electron discharge tube with two gridsor control electrodes.

Referring to the drawing, an electron discharge tube IB is employed with a single equipotential cathode c, a heater filament h, a single anode a, two similarly disposed grids g1, g2, a screening electrode s, and a suppressor electrode t. The tube is therefore equivalent to two pen tode tubes, and with respect to each of the grids g1, the tube may have the characteristics of a standard 6K7 tube, so that it has the same interelectrode constants between each of the grids g1 and g2 and its other electrodes.

The input voltage is applied to the grids g1, 92 by a back coupling arrangement comprising a coil II in the anode circuit and a center-tapped coil l2 with its center tap grounded at l3, and its ends respectively connected through grid leak resistors I4a, Mb shunted by grid condensers l5a, [5b to the grids g1, g2. The two halves of the grid coil I2 are respectively tuned to the input frequency desired by ganged variable condensers l6a, I61). The result of this connection of the coil I2 is that the voltages applied to the grids g1, g2, oscillate in opposing phase, or in other words are out of phase.

In this embodiment, the output circuit of the tube Ill contains the output transformer H, and as an example, the source of potential for the anode a is derived from an alternating current source l8 with a transformer IS with its secondary winding 28 feeding a diode rectifier 2i, and with the rectified output smoothed in conventional fashion by a series inductance 22 and shunt condensers 23. A secondary winding 24 supplies the cathode of the rectifier 2! and another secondary windin 25 supplies the heating filament h of the tube Iii with alternating current. A conventional dropping resistor 33 with one terminal grounded through a condenser 34 is provided for fixing the positive potential of the screen grid s.

The center tap of the secondary winding 20 is grounded at l3 and the cathode c is provided 3 with a bias battery 26 shunted by a condenser 21 which provides a positive bias for the cathode of, for example, 3 volts above the grounded point l3.

This embodiment i a simple embodiment intended to utilise the fundamental frequency to which the circuit 16a, 16b, I2 is tuned, The grids g1, 92 are biased through the center tap of the coupling coil i2 so that the anode current is cut off when the negative voltage on either grid g1 or 92 exceeds a predetermined value. The frequency in the output transformer 11, therefore, is the product of the frequency of the tuned cir cuits l2, Isa, [6b, and the number of gridsqi, ya, that is to say, twice the tuned frequency.

It is clear that the same circuit connections could be employed with two pentode tubes as long as the anodes a are directly connected together, as well as the cathode 0, screen grids s, suppressor grids t respectively connected together.

I claim:

1, A self-excited oscillation generator comprising an electron discharge device comprising an envelope containing a single anode, an electron-emitting cathode and a plurality of control grids, with the same inter-electrode constants between each of said grids and said anode and said cathode, a source of electrical supply, conductors connecting said source to said anode to form an anode circuit, a coupling coilincluded in said anode circuit, a plurality of frequency determim ing tuned circuits coupled with. saidcoupling-coil and yielding a plurality of voltages with mutual phase displacement and connections for applying said voltages respectively to said grids.

2. A self-excited oscillation generator comprising an electron discharge device comprising an envelope containing a single anode, an electronemitting cathode and a plurality of control grids with the same inter-electrode constantsbetween each of said grids and said anode andv cathode, a source of electrical supply, conductors connecting said source to said anode to form an anode circuit, a plurality of frequency determinin tuned circuits each connecting one of said grids to said cathode, and means for coupling said anode circuit to each of said tuned grid circuits for impressing said grids respectively voltages with mutual phase displacements of 360 electrical degrees divided by the number of said grids.

3. A self-excited oscillation generator comprising an electron discharge device comprising an envelope containing a single anode, an electronemitting: cathode and a plurality of control grids With the same inter-electrode constants between each of saidgrids and said anode and cathode, a source of electrical supply, conductors connecting said source to said anode to form an anode circuit, a plurality of frequency determining tuned circuits each connecting one of said grids to said cathode, ganged tuning means for simultaneously tuning said grid circuits, and means for coupling said anode circuit to each of said tuned grid circuits for impressing upon said grids respectively voltages with mutual phase displacements of 360 electrical degrees divided by the number of said rids.

ELAVATHUR SUBRAMANIAN- VISWANATHA-N- PATTAMALY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,848,507 Vos Mar. 8, 1932 2,156,088 Heising Apr. 25, 1939 2,323,672 Nels-on July 6', 1943 FOREIGN PATENTS Number Country Date 638,940 France Feb;,28', 1928 758,865 France Oct. 2, 1933 

